[pox-dev] Help in installing a flow entry

[ramesh oswal]

Sir i am trying to install a flow entry referring to the eg. given in pox
manual to install a flow entry in flow table
 Code used
      msg = of.ofp_flow_mod()
      msg.priority = 42
      msg.match.dl_type = 0x800
      msg.match.nw_dst = IPAddr("192.168.101.101")
      msg.match.tp_dst = 80
      msg.actions.append(of.ofp_action_output(port = 4))
      self.connection.send(msg)
 It is showing me this given warning .
WARNING:libopenflow_01:Fields ignored due to unspecified prerequisites:
tp_dst

Can you help me with this warning

Thank You